Search results for "roche"

Design and Characterization of Effective Ag, Pt and AgPt Nanoparticles to H2O2 Electrosensing from Scrapped Printed Electrodes

2019

The use of disposable screen-printed electrodes (SPEs) has extraordinarily grown in the last years. In this paper, conductive inks from scrapped SPEs were removed by acid leaching, providing high value feedstocks suitable for the electrochemical deposition of Ag, Pt and Ag core-Pt shell-like bimetallic (AgPt) nanoparticles, onto screen-printed carbon electrodes (ML@SPCEs, M = Ag, Pt or AgPt, L = metal nanoparticles from leaching solutions). ML@SPCEs were characterized by scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The results were compared to those obtained when metal nanoparticles were synthesised using standard solutions of metal salts (MS@…

Extraordinary Performance of Carbon‐Coated Anatase TiO 2 as Sodium‐Ion Anode

2015

The synthesis of in situ polymer‐functionalized anatase TiO2 particles using an anchoring block copolymer with hydroxamate as coordinating species is reported, which yields nanoparticles (≈11 nm) in multigram scale. Thermal annealing converts the polymer brushes into a uniform and homogeneous carbon coating as proven by high resolution transmission electron microscopy and Raman spectroscopy. The strong impact of particle size as well as carbon coating on the electrochemical performance of anatase TiO2 is demonstrated. Downsizing the particles leads to higher reversible uptake/release of sodium cations per formula unit TiO2 (e.g., 0.72 eq. Na+ (11 nm) vs only 0.56 eq. Na+ (40 nm)) while the …

Tailoring of the solid state properties of Al-Nb mixed oxides: A photoelectrochemical study

2013

Al-Nb containing mixed oxides were grown by anodizing sputter-deposited Al-Nb alloys of different compositions. A photoelectrochemical investigation was carried out in order to estimate the band gap, flat band potential, and conductivity type of these oxides as a function of their composition. The dependence of the band gap on the composition of mixed sp-d metal oxides has been rationalized by using a semiempirical correlation between the difference of electronegativity and band gap of oxides proposed in the literature some years ago and recently tested for regular d-d metal mixed oxides. The band gap increase observed as a function of Al content into the oxides seems mainly depending on th…

Comparison of local electrochemical impedance measurements derived frombi-electrode and microcapillary techniques

2009

Abstract In the present paper, local electrochemical impedance spectra were obtained on a 316L stainless steel from two configurations: a dual microelectrode (bi-electrode) and microcapillaries. With the bi-electrode, the local impedance measurements were made from the ratio of the applied voltage to the local current density calculated from the application of the ohm's law. With the use of microelectrochemical cells, the specimen surface area in contact with the electrolyte is limited by the use of glass microcapillaries and the local impedance was defined from the ratio of the local potential to the local current restricted to the analysed surface area. Differences and similarities observ…

Sensors for the monitoring of analytes in the sweat

In the last decade, can be found an exceptional growth in research activity relating to the development of wearable devices, capable of continuously monitoring the health conditions of the wearer by analyzing body fluids such as blood, urine, saliva, tears and sweat. Among the body fluids available, sweat is a biofluid of particular interest, as it allows a non-invasive, continuous and comfortable collection. Human sweat contains useful information on the health of an individual and therefore is an excellent biofluid for the detection of specific analytes. The most abundant ions in the sweat are Na+ and Cl- (10 - 100 mM), and their monitoring is useful in patients with cystic fibrosis. Othe…

Constant inner potential DFT for modelling electrochemical systems under constant potential and bias

2021

Electrochemical interfaces and reactions play a decisive role in e.g. clean energy conversion but understanding their complex chemistry remains an outstanding challenge. Constant potential or grand canonical ensemble (GCE) simulations are indispensable for unraveling the properties of electrochemical processes as a function of the electrode potential. Currently, constant electrode potential calculations at the density functional theory (DFT) level are carried out by fixing the Fermi level of the simulation cell. However, the Fermi level from DFT calculations does does not always reflect the experimentally controlled electrode potential or describe the thermodynamic independent variable in G…

Predictive Model for Cut-Edge Corrosion of Galvanized Steels

2006

A numerical model for the electrochemical behavior of cut-edge of galvanized steels is proposed. Some experimental data of current densities above cut-edge immersed in a 0.03M NaCl solution have been measured, using a scanning vibrating electrode technique, and compared with some simulated ones. A good fit has been obtained. The model geometry has been modified by decreasing the electrolyte thickness in order to tend towards an atmospheric corrosion case; such situation that is not easily accessible by electrochemical studies. Three regions can be distinguished according to the efficiency of the galvanic coupling to protect steel.

Gouvernement d'entreprise et comptabilité

1999

L'objectif de cet article est d'une part, de mettre en évidence les limites de l'approche actionnariale du gouvernement des entreprises pour appréhender le rôle de la comptabilité, d'autre part, de montrer l'intérêt d'une approche partenariale comme réponse aux limites de l'approche actionnariale.

ELECTROCHEMICAL H2O2 SENSORS BASED ON Pd and Cu NANOSTRUCUTERS

2018

In the last decades, with the fast improvement of electronics, the field of sensors is highly expanding. The basic idea of sensors is to detect something and then trigger a corresponding action. This simple, but very important, concept can be used in different fields: from chemical industries to farms, from the environmental monitoring [1] to a point of care analysis [2]. Currently, talking about sensing of chemical species, different techniques are used, such as Atomic Absorption Spectroscopy (AAS), Graphite Furnace Atomic Absorption Spectroscopy (GFAAS), Inductively Coupled Plasma Mass Spectroscopy (ICP-MS), IR spectroscopy, redox titration and so on. Despite they are highly efficient in …

Vacuum-Deposited Cesium Tin Iodide Thin Films with Tunable Thermoelectric Properties

2022

Most current thermoelectric materials have important drawbacks, such as toxicity, scarceness, and peak operating temperatures above 300 °C. Herein, we report the thermoelectric properties of different crystalline phases of Sn-based perovskite thin films. The 2D phase, Cs2SnI4, is obtained through vacuum thermal deposition and easily converted into the black β phase of CsSnI3(B-β CsSnI3) by annealing at 150 °C. B-β CsSnI3is a p-type semiconductor with a figure of merit (ZT) ranging from 0.021 to 0.033 for temperatures below 100 °C, which makes it a promising candidate to power small electronic devices such as wearable sensors which may be interconnected in the so-called Internet of Things. T…